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Before You Begin
Dell™ OptiPlex™ GX400 Service Manual
Precautionary Measures
Recommended Tools
Restarting the Computer
Precautionary Measures
Before you remove the computer cover, perform the following steps in the sequence indicated.
1.Turn off your computer and any devices.
2.Disconnect your computer and devices from their power sources. Also, disconnect any telephone or telecommunication lines from the computer. Doing so reduces the potential for personal injury or shock.
3.If you are disconnecting a device from the computer or are removing a component from the system board, wait 10 to 20 seconds after disconnecting the computer from AC power before disconnecting the device or removing the component to avoid possible damage to the system board.
4.Wear a wrist grounding strap, and clip it to an unpainted metal surface, such as the padlock loop on the back of the chassis. If a wrist grounding strap is not available, touch any unpainted metal surface on the back of the computer or on the computer chassis, such as the power supply, to discharge any static charge from your body before touching anything inside the computer. While you work, periodically touch an unpainted metal surface on the computer chassis to dissipate any static electricity that might harm internal components. Also avoid touching components or contacts on a card and avoid touching pins on a chip.
5.Verify that the standby power light on the system board is not on. If it is on, you may need to wait 10 to 30 seconds for it to go out. To locate this light, see
"System Board Components."
Recommended Tools
Some of the procedures in this document require the use of a #2 Phillips- head screwdriver.
Also, use a wrist grounding strap as explained in "Precautionary Measures."
Restarting the Computer
1. Replace the computer cover, reconnect the computer and devices to their electrical outlets, and turn them on.
NOTE: If enabled, the Chassis Intrusion option causes the following message to be displayed the next time you restart your computer:
ALERT! Cover was previously removed.
2.To reset the Chassis Intrusion option, enter system setup, select the System Security option, and reset the Chassis Intrusion option to Enabled or Enabled Silent.
NOTE: When the setup password is enabled, you must know the setup password before you can reset the Chassis Intrusion option.
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